A pixel of an organic light emitting diode (“OLED”) display device includes a switching transistor which transfers a data voltage, a storage capacitor which stores the data voltage transferred by the switching transistor, a driving transistor which generates a driving current based on the data voltage stored in the storage capacitor, an emission control transistor which selectively forms a path for the driving current in response to an emission control signal, an OLED which emits light based on the driving current, and a supplemental electrode overlapping a gate electrode of the driving transistor, the supplemental electrode having a first voltage for a predetermined time period from a time point at which the emission control signal has a turn-on level, and having a second voltage after the predetermined time period.